1. Field of the Invention
The present invention relates to a humidity exchanger capable of providing dehumidified gas, such as dry air, continuously by passing gas through a humidity exchanger element which has a solid adsorbent capable of reversibly absorbing humidity. A humidity exchanger medium is made by including a specific metal in a silicate aerogel formed on a honeycomb matrix of inorganic fiber papers.
2. Description of the Prior Art
In U.S. Pat. Nos. 4,871,607, 4,886,769 and 4,911,775 humidity exchangers are formed from silica or silica-alumina type aerogels impregnated on a laminate of corrugated paper and flat liner paper in the form of a rotary or block honeycomb matrix. As described in U.S. Pat. No. 4,911,775, ceramic fiber papers may be soaked in a waterglass solution, suitably dried, adhered together and then appropriately corrugated to form a laminated corrugated sheet. The laminated sheet is wound or stacked to form a honeycomb matrix which is then sequentially treated with a waterglass solution and an aluminum salt to form an aluminum silicate hydrogel. The honeycomb is then washed and dried to form an aerogel from the hydrogel.
Crystalline titanium silicate molecular sieve zeolites of large and small pore sizes have been disclosed in U.S. Pat. Nos. 4,853,202, 4,938,939 and 5,011,591. Such crystalline materials are expensive, difficult to make, difficult to uniformly incorporate into dehumidifying elements and are not readily regenerated after use.
Accordingly, to further improve the efficiency of humidity exchangers it has been desired to enhance the moisture absorption rate of the aerogel, while reducing the energy required to regenerate the gel matrix after dehumidification use.